1. Technical Field
The present invention relates to a vegetation basis either prepared by mixing a sheath-core type polyester staple fiber with an artificial soil or comprised of a fibrous material, a hot melt adhesive and the balance of bed soil, and a process for production thereof. More specifically, the present invention relates to a vegetation basis which can provide the condition suitable for plant growth by mixing the general commercial, artificial soil with a fibrous material and a hot melt adhesive to form a sponge type netted construct having the crumbled structure, thereby giving the bonding strength to the artificial soil, while has a light weight and further, either has a semi-permanent durability or is degradable within a short period of time, if desired, and to a process for production thereof.
2. Brief Description of the Background Art
The vegetation basis denotes the bases made from artificial soil capable of allowing the plant to germinate, root and grow.
In general, in order to allow the plant to grow such areas as rooftop, vertical wall of buildings, concrete block, bank protection block, concrete slope of tide embankment, etc. there is a need of the artificial ground and construct. Therefore, for eliminating any inconvenience due to addition of the artificial soil and separate complicated and difficult constructs in such areas, and reducing the construction costs the vegetation bases have been used. In addition, the vegetation bases have been widely used to form the vegetation base for preventing the leaching of earth and sand from slopes resulting from the road construction to cut mountains or the river conservation work, by a simple construction work within a short period of time. Furthermore, as recently a shortage of the green zone due to urbanization and the effects of plant, including air cleaning, soundproofing, insulation, etc., have been noted, the attempt to green the vertical exterior walls of buildings or in the soundproofing walls around the road, the bridge piers, the retaining walls of the road, the median strips, etc., with various plants by means of the vegetation mat has been made instead of the simple greening with climbing plants in the prior art.
The most widely used vegetation basis is the vegetation mat. The vegetation mat is manufactured generally by compression molding of the artificial soil into the checkerboard pattern. The artificial soil has been generally used for greening the artificial ground such as rooftops, and in order to facilitate the work with the artificial soil the vegetation mat has been used. When the space such as rooftops is greened using the vegetation mat, due to the insulating effect of plants the energy required for the heating and cooling of buildings can be reduced, the urban heat island to more increase the atmospheric temperature over the city as compared to that in the suburbs can be prevented, and further it is possible to provide the air cleaning effect and the psychological wellbeing to persons.
The major aspects to be considered in the vegetation mat include first the easy handling through maintaining the mechanical shape of the mat or basis at a minimum, and secondly, the permeability, absorbability, drainage and nutrient adsorbability suitable for plant growth, and next, the weight and durability.
The properties for the bed soil as the basic raw material of the vegetation mat should provide with the following requisites, i.e. (1) appropriate water holding capacity and fertilizer holding capacity, (2) optimum permeability to help root respiration, (3) not containing any bacteria, worms and seeds, (4) maintenance of the acidity in the range of weak acidity to neutrality, (5) uniform physico-chemical properties, (6) suitable and uniform particle size of the bed soil, (7) easy handling property, and (8) superiority of block formation (root tangibility).
The artificial soil used for the vegetation mat can be generally classified into the bed soil as the artificial soil required for seedling, and the culture soil as the artificial soil required for plant growth. The bed soil used as the artificial soil has been commercially available from many companies, and typically comprises cocopeat (coir), peat moss, vermiculite, zeolite, perlite, water-soluble fertilizer and antibacterial substances and wetting agents although their compositional ratios may be different from each other.
In the prior art, the vegetation basis has been manufactured in the manner either that the adhesive is added to the artificial soil followed by compression molding or that the artificial soil is wrapped with the natural fiber (e.g. coir). Coir is the cellulose collected from fruits of coconut palm, and has not so much high strength and is relatively elastic and light, and particularly does not well rot in sea water but has the limitation in use as the natural fiber with respect to the strength or weathering resistance.
As the major material for the artificial soil, perlite is extensively used because it has a low density and a low unit cost. Urea resin is generally used as the adhesives. However, the components of the adhesive comprise phenol and formaldehyde, which cause the problem that they may have a bad influence on the growth of plant. Further, when the artificial soil is solidified with using such liquid type adhesives as urea resin, the molding step must perform with using a high pressure, which brings the condition that pores present in the soil disappear. The pores mean the gap between soil particles as one of the physical properties of the soil. As the particle size is larger and uniform, many gaps between particles are present to grow the pores. Since the pores play a role of retaining air and water, it may be said a good soil is the soil in which water absorption and air ventilation are well achieved. Thus, if the pores are reduced, there is the problem that it may have a bad influence on the plant growth.
Depending on the used place and function of the vegetation mat, one of the important factors is the durability. Up to the present, many vegetation mats for greening the vertical wall have been manufactured with the natural fiber and the bed soil. However, upon passing one or more year after manufacturing and disposing the mat there was the problem that the vegetation mat loses its original function because of rottenness itself to reduce the mat to the half and to flow down.
The typical planting methods for the vegetation basis in the prior art are those for mixing, or applying to the surface, the seeds and, in case of the seedlings, for cutting the basis and then digging the contents away and planting the seedlings. Therefore, there was the problem that when the vegetation basis is intended to vertically stand, the contents are more readily discharged through such grating holes to more shorten the durability of said basis.
In order to solve such problems, various alternatives have been suggested. For example, Korean Registered Patent No. 10-0500963 discloses the sedum vegetative mat comprised of a natural fiber net on the back side, an artificial soil layer laid on the surface layer thereof, a sedum trophosome scattered and compressed on the artificial soil layer, and a natural fiber net attached on the surface side of the artificial soil layer; and Korean Registered Patent No. 10-0537293 discloses the vegetation mat manufactured by addition of 40 to 50% by weight of coconut chip, 40 to 50% by weight of coco dust, 1 to 10% by weight of peat moss, 1 to 10% by weight of decomposed bark, natural fertilizer, inorganic-based trace element additives to a coir cloth manufactured utilizing a coir as the fiber collected from fruits of coconut palm, followed by compression molding.
However, said inventions emphasized on the eco-friendly elements to use the natural fiber, wrap the outside of the mat with the net of such natural fiber and then mold the artificial soil under compression. Therefore, since in said methods the artificial soil itself has no adhesive property, there is the problem that the pressure applied for molding a shape of the vegetation mat cause brings about reduction of the pores present in the artificial soil and thus, is not desirable to the plant growth. Further, upon passing one or more year after disposing the vegetation basis on the vertical wall there was also the problem that said basis rots and flows down to so that the original purpose of said basis cannot be attained.
In case of the vegetation mat wrapped with the natural fiber on the outside thereof, it has no difference in the reduction of weight as compared to the light soil used to form the vegetation space, and when the mat is exposed to a sun light or a dramatic change of temperature, the natural fiber net used for preventing the discharge of the artificial soil from the inside of the mat has a low durability due to the limit of natural fibers so that the artificial soil present in the mat may be discharged not long after disposing the mat to make the attainment of the original purpose of the mat difficult and to cause a necessity of the complicated reconstruction. Further, there is also the problem that since the plants are planted after the vegetation holes are cut into the grating form, the contents are more readily discharged from such holes. Such problems are more remarkable particularly when the mat is disposed on the sharply sloped place or on the vertical wall or soundproofing wall. In addition, wrapping the outside of the vegetation mat with the net makes the manufacturing procedures more complicated to ultimately result in an increase of the production unit cost, and use of the coir for the outer net may cause a possibility of inhibiting the absorption of water and nutrients by plants due to the oil fraction membrane of coir.
Further, Korean Registered Patent No. 10-0750564 discloses the vegetation mat which has a rigid grid having the grating net structure and in which the vegetation bed is bonded with the eco-friendly adhesive comprised of 70 to 80% by weight of carboxy methylcellulose, 2 to 15% by weight of the germinating and rooting promoter, and water constituting the balance. However, even though the adhesive is eco-friendly, at least an amount of the adhesive should be used so as to have a minimum bonding strength, and therefore, the components of the adhesive may impede the formation of pores within the vegetation mat, and further, use of such separate construct as the rigid grid, in addition to the vegetation mat, may cause the problem of an increase in the manufacturing unit cost.
In order to maintain the vertical wall for a long period, the non-rotting fibers or frameworks are needed. On the contrary, to cover the construct having a gentle slope such as bank protections or ponds the basis which is readily and rapidly decomposed is needed, since the basis is eco-friendly when the vegetation basis is rotted and decomposed after the plants take root and then the root block is completely established.